Heart failure cardiac output

In heart failure, cardiac output rises again because ventricular afterload diminishes due to a fall in peripheral resistance. Venous congestion abates as a result of (1) increased cardiac output and (2) reduction in venous return (decreased aldosterone secretion, decreased tonus of venous capacitance vessels). 

Lignocaine s clearance by the liver is flow dependent. In heart failure cardiac output may be very low and therefore hepatic blood flow through both the hepatic artery and the portal venous system is also low. This meant a lower extraction of the drug from the blood and accumulation of lignocaine until the high plasma concentration produced the central nervous system toxicity. 

Minoxidil is a more potent vasodilator than hydralazine, and the compensatory increases in heart rate, cardiac output, renin release, and sodium retention are more dramatic. Severe sodium and water retention may precipitate congestive heart failure. Minoxidil also causes reversible hyper-... 

Propranolol Nonselective competitive antagonist at adrenoceptors Decreased heart rate, cardiac output, and blood pressure decreases myocardial oxygen demand Prophylaxis of angina for other applications, see Chapters 10, 11, and 13 Oral and parenteral, 4-6 h duration of action Toxicity Asthma, atrioventricular block, acute heart failure, sedation Interactions Additive with all cardiac depressants... 

Likewise, heart failure is not always associated with systolic dysfunction and an obvious decline in cardiac pumping ability. In approximately half the cases of symptomatic heart failure, systolic function and cardiac output may appear normal when the patient is at rest.53,63 In this type of heart failure, cardiac function is impaired because the left ventricle is stiff and unable to relax during the filling phase, resulting in increased pressures at the end of diastole.31 This condition is often described as diastolic heart failure, but it is also identified by other names such as heart failure with preserved left ventricular... 

Hydralazine may cause a dose-related, reversible lupus-like syndrome, which is more common in slow acetylators. Lupus-like reactions can usually be avoided by using total daily doses of less than 200 mg. Other hydralazine side effects include dermatitis, drug fever, peripheral neuropathy, hepatitis, and vascular headaches. For these reasons, hydralazine has limited usefulness in the treatment of hypertension. However, it may be useful in patients with severe chronic kidney disease and in kidney failure. Minoxidil is a more potent vasodilator than hydralazine, and the compensatory increases in heart rate, cardiac output, renin release, and sodium retention are more dramatic. Severe sodium and water retention may precipitate congestive heart failure. Minoxidil also causes reversible hyper-... 

Because of the ease of introducing intravenous and intra-arterial catheters and measuring blood flow and blood pressure, dogs are commonly used to conduct hemodynamic studies. These studies evaluate the effect of the test compound on systolic and diastolic blood pressure, heart rate, cardiac output, dp/dt, respiration, ECG, and ventricular pressure. From these data, effects desirable for treating angina pectoris, congestive heart failure, coronary vasospasm, and myocardial infarction can be detected. 

A drug which, by its actions on the heart, increases cardiac output and which is therefore used in the treatment of heart failure. It has to be used cautiously because of toxic effects. Elderly patients are particularly sensitive and overdosage occurs frequently, probably due to impaired renal function. Measurement of serum levels is therefore a useful guide to treatment. It can be measured by radioimmunoassay or enzyme-immunoassay. 

Moreover, digitahs has indirect effects on the circulation, which in normal hearts results in a small increase in arterial pressure, peripheral resistance, and cardiac output (114). The effects of digitahs on the circulation of an individual experiencing congestive heart failure are much more dramatic, however. The increased cardiac output, for example, increases renal blood flow which can reheve in part the edema of CHF associated with salt and water retention (114). 

Occurs when the volume of extracellular fluid is significantly diminished. Examples include hemorrhage, fluid loss caused by burns, diarrhea, vomiting, or excess diuresis Occurs when the heart is unable to deliver an adequate cardiac output to maintain perfusion to the vital organs. Examples include as the result of an acute myocardial infarction, ventricular arrhythmias, congestive heart failure (CHF), or severe cardiomyopathy. 

Left ventricular dysfunction, also called left ventricular systolic dysfunction, is the most common fonn of heart failure and results in decreased cardiac output and decreased ejection fraction (the amount of blood that the ventricle ejects per beat in relationship to the amount of blood available to eject). Typically, the ejection fraction should be greater than 60%. With, left... 

Chymostatin-sensitive Il-generating enzyme Carvedilol Post-Infarct Survival Control in Left Ventricular Dysfunction Trial Collaborative Study Captopril Trial ( The Effect of Angiotensin-Converting Enzyme Inhibition on Diabetic Nephropathy ) calcium channel blocking agents Candesartan in Heart Failure Assessment of Reduction in Morbidity and Mortality Trial congestive heart failure, but the latest recommendations use HF for heart failure chronic kidney disease cardiac output... 

Treatment of acute heart failure targets relief of congestion and optimization of cardiac output utilizing oral or intravenous diuretics, intravenous vasodilators, and when appropriate, inotropes. 

Heart failure (HF) is defined as the inadequate ability of the heart to pump enough blood to meet the blood flow and metabolic demands of the body.1 High-output HF is characterized by an inordinate increase in the body s metabolic demands, which outpaces an increase in cardiac output (CO) of a generally normally functioning heart. More commonly, HF is a result of low CO secondary to impaired cardiac function. The term heart failure will refer to low-output HF for purposes of this chapter. 

Upon stabilization, placement of a pulmonary artery (PA) catheter may be indicated based on the need for more extensive cardiovascular monitoring than is available from non-invasive measurements such as vital signs, cardiac rhythm, and urine output.9,10 Key measured parameters that can be obtained from a PA catheter are the pulmonary artery occlusion pressure, which is a measure of preload, and CO. From these values and simultaneous measurement of HR and blood pressure (BP), one can calculate the left ventricular SV and SVR.10 Placement of a PA catheter should be reserved for patients at high risk of death due to the severity of shock or preexisting medical conditions such as heart failure.11 Use of PA catheters in broad populations of critically ill patients is somewhat controversial because clinical trials have not shown consistent benefits with their use.12-14 However, critically ill patients with a high severity of illness may have improved outcomes from PA catheter placement. It is not clear why this was... 

These animal studies should indicate to the pharmacist that blood flow can, under certain circumstances, be an important patient variable that may affect the absorption of drugs. Patients in heart failure would generally be expected to have a decreased cardiac output and, therefore, a decreased splanchnic blood flow. This could lead to a decreased rate of absorption for drugs when the blood flow rates in Eq. (7) become rate-limiting. In addition, redistribution of cardiac output during cardiac failure may lead to splanchnic vasoconstriction in patients [57], Other disease states and physical activity can also decrease blood flow to the GIT [2 4], Thus, the pharmacist must be aware of the possible effect of blood flow rate, especially alterations in the rate, on the availability of drugs. 

It is this reduction in preload that, in some cases, is beneficial to patients experiencing heart failure or hypertension. Unlike a healthy heart, a failing heart is unable to pump all of the blood returned to it. Instead, the blood dams up and overfills the chambers of the heart. This results in congestion and increased pressures in the heart and venous system and the formation of peripheral edema. Because the failing heart is operating on the flat portion of a depressed cardiac function curve (see Figure 14.2), treatment with diuretics will relieve the congestion and edema, but have little effect on stroke volume and cardiac output. 

A patient is considered to be in heart failure when cardiac output is insufficient to meet the metabolic demands of his body. The most effective method to improve cardiac output is... 

VF is electrical anarchy of the ventricle resulting in no cardiac output and cardiovascular collapse. Sudden cardiac death occurs most commonly in patients with ischemic heart disease and primary myocardial disease associated with LV dysfunction. VF associated with acute MI may be classified as either (1) primary (an uncomplicated MI not associated with heart failure [HF]) or (2) secondary or complicated (an MI complicated by HF). 

Decreased cardiac output Heart failure Sepsis Pulmonary hypertension Aortic stenosis (and other valvular abnormalities) Anesthetics... 

Failure Draw this curve below and to the right of the normal curve. Highlight the fall in cardiac output at high LVEDP by drawing a curve that falls back towards baseline at these values. This occurs when cardiac muscle fibres are overstretched. The curve demonstrates that, at any given LVEDP, the cardiac output is less and the maximum cardiac output is reduced, and that the cardiac output can be adversely affected by rises in LVEDP which would be beneficial in the normal heart. 

The cause of death in a human is usually considered to be inadequate cardiac output or inadequate exchange of gases in the lung. Either of these can be caused by failure of function of vital centres in the brain that control the beat of the heart or the act of breathing. Questions as to how a particular disease or trauma leads to failure of these activities are discussed throughout this book. 

In view of the advances in nnderstanding the canse of death in cells, it is somewhat ironic that we understand so little as to what causes death in otherwise healthy humans as they become old (i.e. death due to senescence). In fact, in the UK it is now not permissible to write old age or a similar phrase on a death certificate. The most likely cause of death in humans under most circumstances, is, as indicated above, failure of the vital centres in the brain, e.g. the cells in the brain stem. A suggestion for the cause of death in old age is the progressive decrease in cardiac output with age. Nonetheless, under normal conditions, even a lower cardiac output will not compromise the function of the brain. However, a mild trauma, mild stress or mild infection requires an increase in cardiac output (to support the biochemical changes described in Chapter 18). If this required increase can no longer be attained by the heart in an elderly person, the provision of blood to the brain could be insufficient for this organ. The part of the brain that maintains the essential functions of the body, that is, the brain stem, may be the first to be affected, so that the control of the contraction of the heart or breathing... 

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